Question

on Snapdragon red flower color is incompletely dominant over white flower color the heterozygotes produce pink flower. a red Snapdragon is crossed with a white Snapdragon and the F1 are intercrossed to produce the F2
give the genotype and phenotype
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Answer 1

Answer:

When F1 hybrid exhibit a mixture or blending of characters of two parents, it is called incomplete dominance. For example, in snapdragon one parent is homozygous for red flowers (AA) and the other is homozygous for white flowers (aa). No dominance is present and the heterozygous F1 flowers are pink. The 1: 2: 1 ratio of red, pink and white flowers in the F2 progeny is shown by appropriate colouring.

B. In codominance, both alleles of a pair express themselves fully in F1 hybrid. For example, in cattles when a cattle with red coat is crossed with the cattle having white coat, the F1 hybrid possess roan appearance. In roan appearance, the red and white hairs occur in patches but no hairs have intermediate colour of red and white.

C. Sex chromosomes are primarily concerned with the determination of sex, but these do carry the genes also for other characters. Such characters whose genes are located on the sex chromosomes are known as sex-linked characters. The genes which govern these sex-linked characters are known as sex-linked genes and their inheritance is known as sex-linked inheritance. For example, colour blindness in humans.

D. Pleiotropy is the condition in which one gene produces many effects. In other words, a pleiotropic gene produces a major phenotypic trait and also, it influences some other phenotypic traits.

E. Polygenic inheritance is the condition when many genes control the inheritance of one trait or character. Such genes are called polygenes and show quantitative inheritance. For example, kernel colour of wheat and skin colour in humans.

So, the correct answer is 'Incomplete dominance'.